#10089: Aggregation breaks QuerySet.count() with empty results
-------------------------------------------------------------------+--------
Reporter: Kyle Fox |
Owner: nobody
Status: new |
Milestone: post-1.0
Component: Database layer (models, ORM) |
Version: SVN
Keywords: queryset, execute_sql, aggregation, count, filter, in |
Stage: Unreviewed
Has_patch: 0 |
-------------------------------------------------------------------+--------
When calling `count()` after performing an `__in=[]` filter, a TypeError
is thrown (see example). This is because
[http://code.djangoproject.com/browser/django/trunk/django/db/models/sql/query.py#L262
BaseQuery.get_aggregation ] is attempting to zip
`query.execute_sql(SINGLE)` (line 301), which can evaluate to None in
[http://code.djangoproject.com/browser/django/trunk/django/db/models/sql/query.py#L1914
Line 1933]:
{{{
# Works, even if the filter returns no results.
User.objects.filter(id__in=[1,2,3]).count()
User.objects.filter(id__in=[99,100,101]).count()
# Breaks: Filtering with an empty list and then calling `count()` throws
an error.
User.objects.filter(id__in=[]).count()
}}}
I'm not sure how to fix this problem. I'm assuming that a return value of
`None` is the intended behavior of `execute_sql` in this case, and that
`get_aggregation` should be make more robust to handle a result of None.
--
Ticket URL: <http://code.djangoproject.com/ticket/10089>
Django <http://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To post to this group, send email to django-updates@googlegroups.com
To unsubscribe from this group, send email to
django-updates+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/django-updates?hl=en
-~----------~----~----~----~------~----~------~--~---
